In vivo Cerenkov luminescence imaging: a new tool for molecular imaging

Abstract

Cerenkov radiation is a phenomenon where optical photons are emitted when a charged particle moves faster than the speed of light for the medium in which it travels. Recently, we and others have discovered that measurable visible light due to the Cerenkov effect is produced in vivo following the administration of b-emitting radionuclides to small animals. Furthermore, the amounts of injected activity required to produce a detectable signal are consistent with small-animal molecular imaging applications. This surprising observation has led to the development of a new hybrid molecular imaging modality known as Cerenkov luminescence imaging (CLI), which allows the spatial distribution of biomolecules labelled with b-emitting radionuclides to be imaged in vivo using sensitive charge-coupled device cameras. We review the physics of Cerenkov radiation as it relates to molecular imaging, present simulation results for light intensity and spatial distribution, and show an example of CLI in a mouse cancer model. CLI allows many common radiotracers to be imaged in widely available in vivo optical imaging systems, and, more importantly, provides a pathway for directly imaging b − -emitting radionuclides that are being developed for therapeutic applications in cancer and that are not readily imaged by existing methods.

Cerenkov Luminescence Imaging of Interscapular Brown Adipose Tissue

“…Recently, Thorek et al demonstrated that significantly high sensitivity could be achieved with CLI as low amounts of 18 F-FDG accumulated (about 2Ci) in the nodes of patients 39,40 . In vitro testing indicated that CLI signal from 0.01 Ci 90Y was detectable in solution 25,32,33 . Moreover, CLI also has the potential for high spatial resolution and the capacity for high throughput screening.…”

“…In this protocol, we demonstrate that CLI with 18 F-FDG can be applied for optically imaging BAT in small animals. Like other optical imaging techniques, tissue penetrating limitation and low sensitivity for deep targets are the intrinsic limitations of CLI 25,32 . 39,40 .…”

“…Moreover, CLI can be applied for high throughput screening with an imaging system equipped with high throughput capacity. The advantages and disadvantages of this technology have been discussed in several reviews 25,32,33 . 3D tomography of CLI has been intensively studied in several groups 28,[34][35][36][37] , and the applications of CLI for endoscopic imaging and intraoperative imaging have been successfully demonstrated in mice as well 30,38 .…”

“…Cerenkov luminescence imaging (CLI), a newly emerged molecular imaging technology [18][19][20][21][22][23][24][25][26] , harnesses the luminescence generated from the + and -decay of radionuclides such as 18 F and 131 I in the medium. The charged particle (such as + and -) polarizes molecules while it travels in the medium [18][19][20] , and luminescence/light is emitted when the polarized molecules relax back to equilibrium.…”

On Cherenkov light production by irradiated nuclear fuel rods

“…Ever since its discovery [3], Cherenkov light has become a tool useful in science ranging from physics [4] to biology [5]. Since spent nuclear fuel is frequently stored in water for radiation protection and heat removal, the radiation from the fuel will create Cherenkov light in the surrounding water.…”